MUSCLES 37 



half, Ulnar ; Outer half, Anterior interosseous of median.) 

 [Flexes wrist, metacarpal, phalangeal, and all interphalangeal 

 joints.] Tendons pass beneath annular ligament. 



Flexor longus pollicis : hollow on upper of anterior sur- 

 face of shaft of radius, outer of interosseous membrane for 

 same distance(p) ; base of coronoid process of ulna by a 

 separate slip(p) base of last phalanx of thumb(T) (Anterior 

 interosseous)^ ) [Flexes wrist and all joints of thumb.] Tendon 

 passes beneath the annular ligament. 



Pronator quadratus : anterior surface and anterior border 

 of shaft of ulna, for lower fourth(p) for two inches into lower 

 end of anterior surface and anterior border of radius(p) 

 (Anterior interosseous).^ /[Pronates radius.] 



POSTERIOR, (a) Superficial layer. 



Supinator longus : upper external supra-condylar ridge 

 ofhumerus, external intermuscular septum(p) root of styloid 

 process of radius(x) (Musculo-spiral). [Flexes elbow and 

 pronates or supinates radius from extreme position to midway 

 between pronation and supination.] 



Extensor carpi radialis longior : lower of external supra- 

 condylar ridge of humerus, external intermuscular septum(p) 

 base of posterior surface of 2nd raetacarpal(x) (Musculo- 

 spiral). [Extends elbow, extends and abducts hand.] Passes 

 in groove, posterior to styloid process of radius. 



Extensor carpi radialis brevior : common extensor tendon 

 from external condyle of humerus(x), external lateral ligament, 

 intermuscular septum (F) base of posterior surface of 3rd 

 metacarpal(x) (Posterior interosseous). [Extends elbow and 

 wrist, abducts hand.] 



Extensor communis digitorum : common extensor tendon 

 from external condyle of humerus(x) ; intermuscular septum(F) 

 dorsa of last two phalanges of fingers(x) (Posterior in- 

 terosseous). [Extends wrists and all joints of carpus and 

 fingers.] The four tendons pass through a separate compartment of 

 the posterior annular ligament with the extensor indicts. The tendons 

 of the middle, ring, and little finger are connected by tendinous slips. 



Extensor minimi digiti : common extensor tendon from 

 external condyle of humerus, deep fascia and intermuscular 

 septum(x) 2nd and 3rd phalanges of little finger joining 

 common expansion(x) (Posterior interrosseous). [Extends 

 wrist and all joints of little finger.] Tendon passes through 

 separate sheath of posterior annular ligament, below which it splits 

 into two, the external one being united by a cross-piece with the 

 tendon of common extensor going to little finger. 



